package com.medical.common.security.shiro.filter;

import java.io.Serializable;
import java.util.Deque;
import java.util.LinkedList;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;

import org.apache.shiro.cache.Cache;
import org.apache.shiro.cache.CacheManager;
import org.apache.shiro.session.Session;
import org.apache.shiro.session.mgt.DefaultSessionKey;
import org.apache.shiro.session.mgt.SessionManager;
import org.apache.shiro.subject.Subject;
import org.apache.shiro.web.filter.AccessControlFilter;
import org.apache.shiro.web.util.WebUtils;

import com.medical.modules.sys.security.SystemAuthorizingRealm;

public class KickoutSessionControlFilter extends AccessControlFilter {
	
	private String kickoutUrl;//踢出后到的地址
	private boolean kickoutAfter;//踢出之前登录的/之后登录的用户 默认踢出之前登录的用户
	private int maxSession = 1;//同一个账号最大会话数 默认1
	
	private SessionManager sessionManager;
	private Cache<String, Deque<Serializable>> cache;

	public void setKickoutUrl(String kickoutUrl) {
		this.kickoutUrl = kickoutUrl;
	}

	public void setKickoutAfter(boolean kickoutAfter) {
		this.kickoutAfter = kickoutAfter;
	}

	public void setMaxSession(int maxSession) {
		this.maxSession = maxSession;
	}

	public void setSessionManager(SessionManager sessionManager) {
		this.sessionManager = sessionManager;
	}

	public void setCacheManager(CacheManager cacheManager) {
		this.cache = cacheManager.getCache("shiro-kickout-session");
	}

	@Override
	protected boolean isAccessAllowed(ServletRequest request,
			ServletResponse response, Object mappedValue) throws Exception {
		return false;
	}

	@Override
	protected boolean onAccessDenied(ServletRequest request,
			ServletResponse response) throws Exception {
		Subject subject = getSubject(request, response);
		if (!subject.isAuthenticated() && !subject.isRemembered()) {
			//如果没有登录，直接进行之后的流程
			return true;
		}
		
		Session session = subject.getSession();
		String username = ((SystemAuthorizingRealm.Principal)subject.getPrincipal()).getLoginName();
		Serializable sessionId = session.getId();
		
		//TODO 同步控制
		Deque<Serializable> deque = cache.get(username);
		if (deque == null) {
			deque = new LinkedList<Serializable>();
			cache.put(username, deque);
		}
		
		//如果队列里没有此sessionId, 且用户没有被踢出；放入队列
		if (!deque.contains(sessionId) && session.getAttribute("kickout") == null) {
			deque.push(sessionId);
		}
		
		//如果队列里的sessionId数超出最大会话数，开始踢人
		while(deque.size() > maxSession) {
			Serializable kickoutSessionId = null;
			if (kickoutAfter) {//如果踢出后者
				kickoutSessionId = deque.removeFirst();
			} else {
				kickoutSessionId = deque.removeLast();
			}
			try {
				Session kickoutSession = sessionManager.getSession(new DefaultSessionKey(kickoutSessionId));
				if (kickoutSession != null) {
					//设置回话的kickout属性表示踢出了
					kickoutSession.setAttribute("kickout", true);
				}
			} catch (Exception e) {
				
			}
		}
		
		//如果被踢出了，直接退出，重定向到踢出后的地址
		if (session.getAttribute("kickout") != null) {
			//会话被踢出了
			try {
				subject.logout();
			} catch (Exception e) {
			}
			saveRequest(request);
			WebUtils.issueRedirect(request, response, kickoutUrl);
			return false;
		}
		return true;
	}

}
